[Blue Bowtie]

61 PSIG minimum rail pressure for proper starting.

As somone of prominence would say,"Don't leave home without it."

I've seen them start and run as low as 58 PSIG, but barely, not reliably, and not without problems. Whenever I install a new FPR, I try to set if for 63-65 PSIG under no vacuum, then verify the drop with 15" Hg applied.